<s>
IBM	B-Device
5250	I-Device
is	O
a	O
family	O
of	O
block-oriented	O
terminals	O
originally	O
introduced	O
with	O
the	O
IBM	B-Device
System/34	I-Device
midrange	B-Device
computer	I-Device
systems	O
in	O
1977	O
.	O
</s>
<s>
It	O
also	O
connects	O
to	O
the	O
later	O
System/36	B-Device
,	O
System/38	B-Device
,	O
and	O
IBM	B-Device
AS/400	I-Device
systems	O
,	O
and	O
to	O
IBM	B-Device
Power	I-Device
Systems	I-Device
systems	O
running	O
IBM	B-Application
i	I-Application
.	O
</s>
<s>
5250	O
devices	O
can	O
be	O
directly	O
attached	O
to	O
the	O
host	B-Device
or	O
communicate	O
remotely	O
using	O
Synchronous	B-Protocol
Data	I-Protocol
Link	I-Protocol
Control	I-Protocol
(	O
SDLC	O
)	O
at	O
up	O
to	O
9600bit/s	O
.	O
</s>
<s>
5251	O
and	O
5252	O
input	O
format	O
control	O
attributes	O
are	O
optimized	O
for	O
data	O
entry	O
applications	O
and	O
offer	O
significant	O
enhancements	O
over	O
previous	O
3270	B-Operating_System
terminals	I-Operating_System
.	O
</s>
<s>
System	O
Available	O
light	O
:	O
If	O
lit	O
,	O
this	O
terminal	O
is	O
connected	O
to	O
the	O
host	B-Device
system	O
and	O
is	O
receiving	O
information	O
from	O
it	O
.	O
</s>
<s>
Insert	B-Device
light	O
:	O
The	O
Insert	B-Device
key	I-Device
has	O
been	O
pressed	O
.	O
</s>
<s>
Press	O
Insert	B-Device
again	O
to	O
cease	O
Insert	B-Device
Mode	I-Device
.	O
</s>
<s>
Caps	B-Device
Lock	I-Device
light	I-Device
:	O
The	O
Caps	B-Device
Lock	I-Device
key	I-Device
has	O
been	O
pressed	O
.	O
</s>
<s>
Keyboard	O
Shift	O
light	O
:	O
The	O
Shift	B-Device
key	I-Device
is	O
being	O
pressed	O
.	O
</s>
<s>
The	O
5250	O
is	O
a	O
block-oriented	O
terminal	O
similar	O
to	O
,	O
but	O
not	O
compatible	O
with	O
,	O
the	O
IBM	B-Operating_System
3270	I-Operating_System
.	O
</s>
<s>
The	O
5250	O
data	O
stream	O
definition	O
has	O
been	O
refined	O
over	O
time	O
to	O
include	O
GUI	B-Application
elements	O
such	O
as	O
pop-up	O
windowing	O
,	O
check	O
and	O
option	O
boxes	O
,	O
mouse	O
handling	O
,	O
and	O
pull-down	O
menus	O
.	O
</s>
<s>
A	O
protocol	O
called	O
the	O
IBM	B-Device
5250	I-Device
Data	O
Stream	O
interpreted	O
field	O
attributes	O
such	O
as	O
blinking	O
,	O
non-display	O
,	O
high	O
intensity	O
,	O
reverse	O
image	O
,	O
underline	O
,	O
and	O
column	O
separators	O
and	O
was	O
used	O
in	O
combination	O
to	O
create	O
colors	O
.	O
</s>
<s>
Few	O
physical	O
5250	O
terminals	O
with	O
their	O
bulky	O
twinax	O
cables	O
still	O
exist	O
,	O
although	O
they	O
are	O
occasionally	O
still	O
used	O
to	O
provide	O
a	O
"	O
connection	O
of	O
last	O
resort	O
,	O
"	O
hard-wired	O
to	O
the	O
host	B-Device
computer	I-Device
.	O
</s>
<s>
Today	O
,	O
it	O
is	O
more	O
common	O
to	O
use	O
PC	O
or	O
web-based	O
terminal	B-Application
emulation	I-Application
packages	O
that	O
can	O
interpret	O
and	O
display	O
5250	O
data	O
streams	O
.	O
</s>
<s>
Telnet	B-Protocol
5250	O
,	O
or	O
TN5250	O
describes	O
either	O
the	O
process	O
of	O
sending	O
and	O
receiving	O
5250	O
data	O
streams	O
using	O
the	O
telnet	B-Protocol
protocol	O
or	O
the	O
software	O
that	O
emulates	O
a	O
5250	O
class	O
terminal	O
communication	O
via	O
that	O
process	O
.	O
</s>
<s>
TN5250	O
allows	O
a	O
5250	O
terminal	B-Application
emulator	I-Application
to	O
communicate	O
over	O
a	O
TCP/IP	B-Protocol
network	I-Protocol
instead	O
of	O
an	O
SNA	B-Architecture
network	O
.	O
</s>
<s>
Standard	O
telnet	B-Protocol
clients	O
cannot	O
be	O
used	O
as	O
a	O
substitute	O
for	O
TN5250	O
clients	O
,	O
as	O
they	O
use	O
a	O
different	O
data	O
stream	O
format	O
.	O
</s>
<s>
An	O
interface	O
was	O
created	O
to	O
connect	O
to	O
the	O
Twinax	O
port	O
of	O
a	O
5250	O
terminal	O
and	O
communicate	O
with	O
it	O
like	O
an	O
AS/400	B-Device
host	B-Device
.	O
</s>
<s>
It	O
currently	O
provides	O
VT52	B-Application
emulation	O
and	O
a	O
shell	O
on	O
the	O
system	O
to	O
which	O
the	O
adapter	O
is	O
connected	O
.	O
</s>
<s>
The	O
IBM	O
3179	O
exists	O
as	O
a	O
3270	B-Operating_System
and	O
a	O
5250	O
terminal	O
.	O
</s>
<s>
The	O
IBM	O
3180	O
exists	O
as	O
a	O
3270	B-Operating_System
and	O
a	O
5250	O
terminal	O
.	O
</s>
<s>
An	O
external	O
monitor	O
is	O
connected	O
via	O
VGA	B-Protocol
.	O
</s>
<s>
An	O
external	O
monitor	O
is	O
connected	O
via	O
VGA	B-Protocol
.	O
</s>
